Mira is a red giant star in the constellation Cetus. It is the prototype of the Mira variable star class. Mira also has a companion white dwarf, Mira B. Mira A was the second largest known star in 1925, surpassed by only Antares. Mira A was previously thought to be a red supergiant star but is now known to be only a red giant. In 1997, the Hubble Space Telescope imaged the Mira system. Mira A is quickly losing mass, shedding material into space.
Astronomical data
Mira A
Radius (in Solar Radii): 402 R☉
Diameter (in Kilometers): 559,584,000 km
Mass (in Solar Masses): 1 M☉
Distance (in Light Years): 300 ly
Spectral type: M7 IIIe (Red)
Mira B
Radius (in Solar Radii): 0.015 R☉
Diameter (in Kilometers): 20,880 km
Mass (in Solar Masses): 0.24 M☉
Spectral type: DA (White Dwarf)